Can I also suggest after the descale...you run a load with a few drops of clove oil in it just to make sure any remaining mould spores are killed off...bleach doesn't kill mould it just bleaches it white so you can't see it anymore.....sounds like your machine needs a clove oil rinse as well.

I have never used fabric softener at all....do you really need to, like do you have hard water in your area?